Entire development teams consist of such bad developers. Many of us worked in such teams at one time or another, and it's part what makes us so obsessed with quality and good development practices.
We're dealing with the unprecedented reality that software is already everywhere, but the process of identifying and training good developers has barely started. Most companies that develop software don't even supply their programmers with the proper tools and work environment. It's like living in a world where everyone has a car, but only 90% of all mechanics aren't capable of doing more than just applying some duct-tape, and most garages are ill-equipped barns.
Most software is appallingly badly made, and has a very short lifespan.
And no, this is not just because technology moves so fast. Most of the languages we code in are almost 20 years old, and the techniques and conventions for coding in them even older. Core architectures are based on design conventions that existed before most of us started programming. The fast innovation mostly happens around the edges.
Software development is a ridiculously immature profession compared to it's social and economic importance, and the majority of programmers are as incompetent as a neanderthal with a chemistry set.